Antibiotic disc distributors

ABSTRACT

A distributor for the simultaneous deposition of a plurality of discs or pastilles on a surface in a predetermined configuration comprises a base in relation to which a tube carries drum is adapted to turn in order to effect the extraction and positioning of a respective disc in line with a plurality of axial passages in the base, and also an operating button carrying axial ejection rods the rotation of which causes the drum to turn and the pressure of which effects the simultaneous ejection of the discs through the said passages.

United States Patent [1 1 [111 3,836,047 Darpentigny et al. 1 Sept. 17, 1974 ANTIBIOTIC DISC DISTRIBUTORS [56] References Cited [75] Inventors: Charles Darpentigny, lgny; Michel U T D STA ES PATENTS Iiessegeur, virynchzltlillon; Daniel 3,394.846 7/l968 Ctll'ski ct al 221/265 x ux, agneux, a o rance [73] Assigneez ANVAR Agence Nationale de Primary ExaminerS tanley H. Tollberg valorisafion de la Recherche, Attorney, Agent. or FlrmYoung & Thompson Neuilly-Sur-Seine, France [57] ABSTRACT 22 Fl (1: A .23 1973 1 l 8 ug A distributor for the simultaneous deposition of a plu- PP NOJ 390,941 rality of discs or pastilles on a surface in a predetermined configuration comprises a base in relation to [30] Foreign Application Priority Data which a tube carries drum is adapted to turn in order S 5 1972 F 72 31409 to effect the extractlon and positioning of a respective l973 France 462 disc in line with a plurality of axial passages in the e rance 7 base, and also an operating button carrying axial ejection rods the rotation of which causes the drum to mm and the pressure of which effects the Simulm [58] Field j 265 197 neous ejection of the discs through the said passages.

21 Claims, 24 Drawing Figures E K: 60' 6: 2317 if PAIENIEussH 11914 3366047 SHEET 3 UF 8 FIG] ll ANTIBIOTIC DISC DISTRIBUTORS BACKGROUND OF THE INVENTION The present invention relates to distributors for pastilles or discs, such as those intended to be deposited in mutually clearly defined positions on the surface of agar media used for the preparation of antibiograms.

Antibiotic disc distributors have already been proposed in which the discs, stacked in a series of tubes disposed around an axis above the surface of agar media, are driven radially out from the axis by means of deformable ejection blades engaging at the base of each tube under the action of a push-rod. However, the radial component thus imparted to each disc as it leaves the respective tube does not enable it to be positioned accurately and regularly on the surface of the agar medium. Furthermore, the ejection of the disc out of each tube on each operation of the push-rod can be effected reliably only if the aforesaid ejection blades, which are very fragile, retain very accurate positioning in relation to the base of the tube, so that the operation of the distributor is subject to irregularity.

A main object of the invention is to provide a distributor of the aforesaid kind which is free from these disadvantages, and which has a simple and compact arrangement and ease of operation.

SUMMARY According to the invention a distributor for discs or pastilles, of the kind intended to deposit simultaneously on the surface of an agar medium a plurality of the said discs or pastilles in a predetermined configuration comprises a base having an upper face and a lower face as well as a plurality of suitably spaced ejection passages extending between the said faces, a tube carrier unit provided with a corresponding plurality of sockets for tubes containing the said discs or pastilles, and with a plurality of guide bores, the said unit having a base face adapted to co-operate with the upper face of the base so as to effect, through relative displacement of the said base face parallel to the said upper face, the extraction of a disc or pastille at the base of each of the tubes mounted in the said sockets and the positioning of the said disc at the top end of a corresponding ejection passage; a plurality of ejection rods each of which is axially slidable in one of the aforesaid guide bores so as to cooperate with a corresponding ejection passage; and an operating element mounted for axial sliding at right angles to the upper face of the said base, this operating element being kinematically associated with the said tube carrier unit and with the said ejection rods in such a manner as to make it possible to effect in succession the aforesaid relative displacement of the tube carrier unit and the penetration of the said ejection rods through the said ejection passages.

In order to effectthe extraction of a disc from each tube by displacement of the tube carrier unit in relation to the base, the upper face of the latter advantageously has extraction and positioning projections disposed on each side of each ejection passage, in such a manner as to co-operate with the base of each tube so as to effect the extraction of a disc and to retain it in line with a corresponding ejection passage through the action of the aforesaid relative displacement.

In an embodiment of the invention which is more particularly adapted to the case where the agar medium on which the discs are to be deposited is contained in a Petri dish of circular shape, the aforesaid base has a body of generally cylindrical shape and the tube carrier unit is a drum mounted for free rotation on the said base and kinematically fastened in respect of rotation to the aforesaid operating element by means of the ejection rods with the aid of a crown supporting the upper end of each of the ejection rods.

In another embodiment of the invention more particularly adapted to the case where the Petri dish is of rectangular or square shape, the tube carrier unit is mounted for free movement of translation on the upper face of the base.

In both cases, the extraction of a disc from each tube, through displacement of the tube carrier unit parallel to the upper face of the base, and the ejection of each tube thus extracted through the downward movement of the ejection rods are two quite distinct operations effected in succession, so that the ejected discs can be applied to the agar medium withstrict accuracy.

These two operations are carried out under the action of the same operating element, which preferably co-operates with cam means making it possible to effect these two operations in succession through the action of the same axial pressure applied to the operating element.

Means may be provided to make it possible to prevent the operation of the distributor when at least one of the tubes mounted in the tube carrier unit contains no more discs. For this purpose, the base of the distributor may be provided with a plurality of blocking bores, each of which is adapted to co-operate with a corresponding tube in the tube carrier unit, in order to effect the blocking of the said unit in relation to the base through engagement in the said bore of a blocking element disposed in each tube in such a manner as to project at the base of the latter after extraction of the last disc contained in the tube.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an axial cross-section through a distributor according to the invention, taken on the line II in FIG. 3;

FIG. 2 is a view in cross-section taken on the line IIII in FIG. 1;

FIG. 3 and 4 are plan views respectively of the base and operating button of the distributor shown in FIG.

FIGS. 5 and 6 are respectively a longitudinal crosssection through, and an end view, of one of the tubes intended to be loaded into the drum of the distributor shown in FIGS. 1 to 4;

FIG. 7 is a perspective view of the base of one of the tubes shown in FIGS. 5 and 6; and

FIGS. 8a and 8b are partial axial cross-sections of the upper and lower positions respectively, of an alternative form of construction of the ejection rods of the distributor shown in FIG. 1;

FIG. 9 is an axial cross-section through another form of construction of the distributor shown in FIG. 1, taken along the line IX-IX in FIG. 11 and shown in its position of rest;

FIG. 10 is an axial cross-section of the distributor of FIG. 9 in its ejection position;

FIG. 11 is a cross-section through the drum of the distributor of FIGS. 9 and 10;

FIG. 12 is a section along the line XII-XII in FIG. 14, of a second form of construction of a distributor according to the invention, which is shown in the upper position;

FIG. 12a is a partial view in elevation taken in a plane orthogonal to that of FIG. 12;

FIG. 13 is a view in vertical section taken on the line XIII-XIII in FIG. 14;

FIG. 14 is a view in horizontal section, partly cut away, taken on the line XIV-XIV in FIG. 12;

FIG. 15 is a view similar to FIG. 12, showing the distributor in the lower position;

FIG. 16 is a partial view in vertical section taken on the line XIIIXIII in FIG. 13, showing the relative position of the ejection rods and tubes of the distributor in the lower position of the latter;

' FIG. 17 is a partial view in horizontal section on the line XVII-XVII in FIG. 15;

FIGS. 18 and 19 are partial views in vertical section taken respectively on the lines XVIII and XIX in FIG. 17;

FIG. 20 is a partial view in vertical section taken on the line XX in FIG. 14;

FIG. 21 is a view in vertical section taken on the line XXIXXI in FIG. 14; and

FIG. 22 is a partial view in section in the same plane as FIG. 13, showing a modified construction of the disc carrier tubes and base of the distributor of FIGS. 12 to 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 7, the distributor indicated generally by 10 has an axial symmetry with the axis 11 and it is formed of three mutually movable and coaxially disposed parts, these being a base 12, a tube carrier magazine 14, and an operating button 16.

The base 12, preferably of moulded material, has a cylindrical body 18 with parallel faces and is threaded on its periphery to receive a support ring 19 intended to rest on the edge of a Petri dish of round shape (not shown), thus making it possible to adjust the height of the bottom face 20 of the body 18 above the surface of the agar medium contained in the dish. The upper face of the base 12 has around its periphery a first axial extension which forms an annular flange 21 intended to effect the external guiding of the drum 14, and in its central region has a second axial extension which forms a tube 22 for the internal guiding of the drum 14 and external guiding of the button 16. In the proximity of the periphery of the body 18 are provided eight axial bores 23 regularly spaced on a circle centred on the general axis 11 of the device. These bores constitute ejection passages for the discs to be deposited on the surface of the agar medium, and their diameter is very slightly smaller than that of the discs. Although, in the device illustrated, eight bores are shown, the number could be different from that given herein as an example, and moreover the bores could be disposed on two or more concentric circles instead of on a single circle. The number of bores corresponds to the number of tubes carried by drum 14.

The drum 14, which is preferably of moulded material, is a cylindrical block mounted so as to be able to perform a limited rotational movement in relation to the base 12 and for this purpose has a central bore 24 in which is engaged for smooth sliding the tubular extension 22, its rotational guidance being supplemented. as indicated above, by the annular flange 21 of the base. The drum 14 has a first series of eight axial bores 23a disposed in such a manner as to be exactly in line with corresponding passages 23 when the drum is in its position of rest, this position being determined by a stop pin 25 which is fastened to the base and engages in a cavity 26 having the shape of an arc of a circle and provided in the bottom face of the drum so as to limit its angular travel in relation to the base. The central region of the bottom face of the barrel is, in addition, provided with an annular cavity 28 intended to accommodate a spiral return spring 30, the ends of which are engaged in holes 31, 31a provided respectively in the upper face of the base and the lower face of the drum. On a circle of the same radius as that formed by the centres of the bores 23a the drum has a second series of eight axial bores 32 so disposed as to come into line with the ejection passages 23 of the base when the end 26b of the cavity 26 strikes against the pin 25.

Each of the bores 32 constitutes a socket to receive a tube 35 containing a stack of discs adapted to be extracted one at a time at the base of the tube in a manner which will be described below. Each tube must be accurately positioned angularly and axially in its socket, and for this purpose it is provided with a lateral stud 36 (FIG. 5) co-operating with an axial groove 37 (FIG. 3) provided along each of the bores 32. In order to effect the axial locking of the tubes in their sockets, the stud 36 is provided in its middle region with a notch 38 intended to co-operate with a ring 40 which is engaged in an annular groove 41 in the in the drum.

At its base, each tube has two retaining projections 43, which are situated in the same plane perpendicular to the axis of the tube and have two parallel, opposite edges 44. When the tube is correctly positioned in the drum 14, these two edges are directed in the tangential direction of the angular travel of the drum. As can be seen more clearly in FIG. 7, the projections 43 are so shaped as to retain axially the discs contained in the tube, but to allow them to be extracted laterally one at a time. In order to effect this extraction through the simple pivoting of the drum, the upper face of the base 12 is provided with projecting annular zones 46 of rectangular section, which extend circumferentially between the consecutive passages 23 and together form a circular crown, on each side of which the projections 43 of the tubes 35 are engaged when they are correctly positioned in the drum. In the position of rest of the latter the base of the tubes is situated in line with a projection 46, which penetrates between the two projections 43 on each of the tubes and applies direct pressure to the end disc' 48. When the drum pivots in the direction of the arrow F, the tubes arrive opposite a corresponding ejection passage 23, and then the drum returns to its original angular position through the action of the return spring 30, the end disc 48 of each of the tubes having being retained in line with the passage 23, between the ends of the two projections 46 adjoining this passage. The distributor is thus armed.

The rotation of the drum and the ejection of the discs are both effected by the operation of the button 16, which has a cylindrical head 51 provided with a hollow axial rod 52 engaged slidably in the guide tube 22 of the base. At the bottom the head 51 widens into a crown 54 of generally conical shape. The button 16 is returned in the upward direction by a spiral spring 56 bearing against the top face of the drum l4, and its upper position is defined by a stop screw 58 the head 59 of which co-operates with a shoulder 60 in the axial bore in the button 16. The screw 58 is screwed into the base 12. On its periphery the crown 54 has a first series of eight axial bores 32a intended to permit the charging of the barrel with the tube 35, and a second series of eight axial bores 23b in which the threaded bases 60 of eight cylindrical ejection rods 62 are engaged, these rods engaging slidably in the corresponding bores 23a in the drum and in addition being able to pass through the ejection passages 23 when pressure is applied to the button 16, thus driving out the discs which had been extracted from each of the tubes by a previus rotation during which the ejection rods 62 secure the drum kinematically to the button.

The axial travel of the button 16 in the direction of the drum 14 is limited by an annular shoulder 65 which is provided at the base of the head of the button and comes into contact with the end face of the guide tube 22. The axial length of this travel is so selected that when the button is in the upper position the lower ends of the ejection rods 62 are situated just above the bottom face of the drum and that, in the lower position, this lower end projects slightly beyond the lower face of the base 12, thus accompanying over the greatest possible height that descending travel of the eight discs simultaneously ejected, without causing any risk of passing through the surface of the agar medium. The positioning of the discs thus deposited on this surface can thus be made very accurate.

The operation of the distributor described above is as follows. After the drum has been charged by disposing the tubes 35 in their sockets and after the ring 19 has been so adjusted that the lower face 20 of the base 12 is at a suitable height above the surface of the agar medium, the distributor is armed by turning the button 12 in the direction of the arrow F, and it is allowed to return to its original angular position under the action of the return spring 30. Each ejection rod 62 then comes once again in the axis of a corresponding ejection passage 23, at the inlet of which is disposed a disc extracted from a corresponding tube 35. The button 16 is then pressed and each ejection rod passes through a passage 23, pushing a disc in front of it and accompanying the disc over the greater part of its descending travel. The eight discs are consequently deposited on the surface of the agar medium while substantially retaining their original relative arrangement, namely the arrangement of the passages 23.

The modification illustrated in FIGS. 8a and 8b is intended to enable the end of the ejection rods to accompany the downward movement of the discs until they come into contact with the free surface 100 of the agar medium, in order to effect the intimate application of the surface of each disc against that of the agar medium, without any risk of bursting the surface of the latter. For this purpose each of the ejection rods 102, which are used in place of the previously described rods 62, is composed of a cylindrical sleeve 103 in the bottom end of which a push-rod 105 constituting the actual ejector is adapted to slide. The push-rod 105 has a cylindrical body 106 provided with a pin 107 cooperating with a slot 108 provided in the wall of the sleeve 103 in order to define its axial movement in relation to the latter. Against the back surface of the body 106 is applied a pressure spring 109 which bears at its upper end against the stopper 110 screwed into the sleeve 10.3, the latter in turn being screwed into a tapped bore 112 and the crown 114, which may otherwise be similar to the crown 54 previously described. At its bottom end the push-rod 105 has an annular shoulder 116 whose diameter is substantially equal to the outside diameter of the sleeve 103, this outside diameter being in turn substantially equal to, but less than, the inside diameter of the ejection passages 23 (FIGS. 1 and 3).

The pin 107 and the slot 108 are so disposed as to define only the bottom position or extension position of the push-rod 105 in relation to the sleeve 103, as can be seen in FIG. 8a, the retracted position of the pushrod in relation to the sleeve being defined by contact between the shoulder 116 and the bottom end of the sleeve 103. The axial travel defined between these two end positions is of the order of a few millimetres, that is to say very short in relation to the length of the spring 108. This being the case, the spring 108 works practically with constant tension. Taking into account the surface of the push-rod, the value of this tension is selected to be sufficient to apply each disc effectively against the agar medium (FIG. 8b) but insufficient to pass through the surface of the latter.

The operation of the ejection rods 102 is as follows. In the position of rest or upper position of the distributor crown in relation to the base 12 the push-rods are in their position of extension and their lower end is situated in the drum l4 slightly above the upper face of the base 12 (FIG. 8a). When, after the arming of the distributor, the button 16 is depressed, the bottom face of each push-rod comes into contact with a respective disc, which imparts to it a reaction which is in general greater than the tension of the corresponding spring 108, so that the descent of the push-rod is stopped until the lower end of the sleeves 103 comes to bear against the annular shoulders 116, thus transmitting direct to the push-rod the pressure applied to the button 16. Each of the discs is consequently forced along the passages 23. When the discs reach the bottom end of the passages 23, the springs 108 can expand, and after the locking of the sleeves 103 in the lower position the push-rods accompany the ejected discs in their downward movement until the discs are applied against the surface 100 of the agar medium (FIG. 8b), and the movement of extension of the push-rods is then stopped by the reaction force which is thus applied thereto. The relative height of the base 12 in relation to the surface of the agar medium is, of course adjusted, prior to this operation by means of the ring 19 (FIG. 1) in such a manner that, in the arrival configuration illustrated in FIG. 8b, the push-rods 105 are not in their position of maximum extension.

The distributor 200 illustrated in FIGS. 9 to 11 is intended to make it possible to effect the arming and the ejection of the discs in a single operation. Its general arrangement is nevertheless very similar to that described with reference to FIGS. 1 to 7, and will therefore not be described in detail again. In the upper position or position of rest of the operating button 216 of the distributor 200, the tubes 35 disposed in the drum 214 are situated in the axis of the ejection passages 223 of the base 216, and the rotation of the drum, which effects the arming of the device, is combined with the downward movement of the ejection rods 262 (FIG. 9) with the aid of one or more profiled grooves 202 which are provided in the wall of the guide tube 222 extending the base, and which co-operate with a pin 204 carried by the axial extension 252 of the button. The profiled groove 202 comprises a first axial portion 202a intended to permit the assembly of the device, a second inclined, rectilinear or helicoidal portion 202b intended to define the angular travel of the drum in relation to the base, and a third axial portion 2020 intended to define the useful axial stroke of the ejection rods 262, the latter naturally being situated in the axis of the passages 223 when the pin 204 is engaged in the portion 202c of the profiled groove or grooves. In the embodiment described herein the number of tubes 35, and consequently the number of rods 262 and of bores 263, is still equal to eight. Nevertheless, the angular travel of the barrel may be much shorter than in the case of the distributor of FIGS. 1 to 7, and it is for this reason that, as can be seen in FIG. 11, the bores 232 and 223a respectively provided in the drum 214 to receive the tubes 35 and the rods 62 are not necessarily equidistant in relation to one another. The angular travel of the drum 214 being defined by the profile 202 (inclined portion 202b), the pin 25 and the cavity 26 which fulfil this function in the distributor can be eliminated here, which is also true of the spring 30, since the angular return of the drum 214 is effected by kinematic connection to the axial return of the button 216 under the action of the spring 256. In order to make the operation of the button 216 more convenient, its head 251 is made freely rotatable in relation to the crown 254, means, such as a pin 205 co-operating with an annular groove 206, being provided in order to effect the axial fastening of the button in relation to the crown.

The operation of the distributor 200 is as follows. When the button 216 has been depressed axially, the axial thrust thus transmitted to its axial extension 252 causes the pin 204 to travel along the inclined region 2020 of the groove 202, thus imparting to the crown 254 a movement of rotation in the direction of the arrow F. This movement is transmitted to the drum 214 by the ejection rods 262, and the tubes 35, which were originally situated in the axis of the corresponding bores 223, describe an arc of a circle in relation to the base and, because of the presence of the annular projections 246 whose arrangement is identical to that of the projections 46 in FIG. 3, leave a disc in line with each of the bores 23. The device is thus armed. When the pin 204 arrives at the top end of the rectilinear portion 202a of the groove, the ejection rods are situated in the axis of the passages 223 and the continuation of their downward movement, guided in relation to the base by the pin 204, effects the ejection of the discs. When the button 216 is released, the same operations are effected in the reverse order through the action of the return spring 256. Obviously, the tubes 35 do not give up a disc during the return movement, because the projection 246, on which their bottom end slides, has an interruption only in line with the passages 223, that is to say in a position which the tubes occupy only in the configuration of rest of the device.

The distributor illustrated in FIGS. 12 to 21 has a generally rectangular shape and is intended to effect, through the same operation of applying axial pressure to an operating button 312, the deposition of sixteen antibiotic discs, originally contained in charger tubes 314, on the surface 315 of the agar medium 316 contained in a Petri dish 318 of square shape which can be disposed vertically in line with the base 320 of the distributor, in the bottom portion of which a cavity 321 is provided to receive a dish of this kine. The base 320 has the general shape of a rectangular plate which is provided with sixteen cylindrical ejection passages 322 regularly disposed at the nodes of a two-dimensional network of square mesh, this being a mutual arrangement which likewise applies to the tubes 314 received in the bores 324 of a tube carrier unit 325 and to the ejection rods 327 (FIGS. 13, 16 and 17) mounted on a plate 330 in such a manner as to be able to slide conjointly in bores 332 provided in the tube carrier unit I At right angles to its upper face 334 the base 320 has in its central region a tubular extension or barrel 335 intended to effect the guiding of the operating button 312. At its top the latter has a flattened head 336, which is extended downwards by a hollow rod 337 engaging over the guide barrel 335. The button 312 is returned to its top position by a spiral spring 339, and its axial travel is limited by a shoulder 340 whose upper face co-operates with the head of an assembly screw 341 screwed into the base 320, and whose lower face co-operates with the top end of the barrel 335.

The tube carrier unit 325 has the general shape of a right parallelepiped. Its base face 343 rests on the upper face 334 of the base, in relation to which it is capable of a horizontal movement of translation between the end positions shown respectively in FIGS. 12 and 15, for the purpose of effecting the extraction of a disc at the base of each of the tubes 314 and its positioning in line with the inlet of a corresponding ejection passage 322. The unit 325 is provided in its central portion with a passage 345 for the barrel 335 and the rod 337; one of the walls of this passage (the left-hand wall in FIGS. 12 and 15) defines in its upper portion an inclined plane 346 forming a cam which co-operates with a stud 347 projecting laterally from the free end of the rod 337, so that when the button 312 is pressed the downward movement of the stud 347 bearing against the inclined plane 346 effects, in the initial portion of its travel, the translatory movement of the unit 325 towards the left. In the course of this movement of translation the tubes 314, which were originally situated in line with the ejection passages 322, (FIG. 13), in each case leave there a disc (not shown) as the result of the provision of the projections 350 having a rectangular profile (FIGS. 14 and 18) which extend in four rectilinear rows on the upper face of the base and co-operate with the tubes 314 in the manner previously described with reference to FIGS. 1 to 11. These projections serve in addition as guide profiles for the movement of the carrier unit, and for this purpose they co-operate with grooves 352 provided in the bottom face of the unit 325 (FIG. 20).

The tubes 314, which have a projection 354 for the purpose of angular positioning and locking, are held in position in the bore 324 receiving them by means of two rings 355, each of which effects the locking of eight tubes and is accommodated in a recess 356 in the upper face of the unit 325 (FIG. 17). This recess receives a flush fitting retaining plate 357 provided with notches 358 in the shape of an arc of a circle in line with the corresponding bores 324.

The unit 325 is held on the base 320 by means of two lateral screws 360 (FIGS. 17 and 21) and a middle screw 361 (FIG. 12) which are screwed into the base and received in slots 362 providing in the tube carrier unit the necessary clearance to permit it to slide. The width of the corresponding travel, indicated by the arrow 365 in FIGS. 13 and 17, is equal to the spacing between each of the sixteen bores 324 and the bores 322 associated therewith. The screws 360 and 361 have a flat head 367 which is flush with the upper face of the unit 325 and effects its retention on the base 320.

On the lateral screws 360 is fixed one end of a helical tension spring 370 (FIG. 21) the opposite end of which is fixed on the base by means not shown. The two springs 370 are received in sockets 372 provided in the bottom face of the unit 325 vertically in line with the retaining plates 357 (FIG. 17), and effect the return of the unit 325 to the position of rest shown in FIG. 12.

The plate 330, which is intended to effect the simultaneous downward movement of the sixteen ejection rods 327 in the corresponding passages 322, is formed of two superimposed rectangular plates 375 and 376 whose edges coincide with those of the unit 325 and which accompany the latter in its movement of translation in relation to the base. The plate 330 is mounted for vertical sliding on the unit 325 by means of two lateral screws 378 (FIGS. 17 and 21) and of a middle screw 379 (FIGS. 12 and 14), against the heads of which screws the retaining plate 376 abuts in its upper position of rest (FIGS. 12 and 21) because of the pressure of a corresponding return spring 380, the upper end of which bears against the lower face of the plate 375, while its lower end is received in a cylindrical cavity provided in the unit 325 coaxially to the screws 378 a and 379.

For the reasons previously indicated with reference to FIGS. 8a and 8b, the ejection rods 327 may undergo a limited axial displacement in relation to the plate 330. In the present case they are for this purpose composed of a hollow sleeve 382 which is closed at its free end 383 and in which is disposed a compression spring 384 the top end of which bears against the inner face of the retaining plate 376. The sleeves 382 are received at their upper end in a respective cylindrical socket 386, the bottom end of which cooperates with an angular retaining shoulder 388 formed at the upper end of each sleeve 382. Each ejection rod can thus slide in the plate 330 over a height close to that of its socket 386, its axial alignment being effected by the bore 332 situated vertically in line with the socket.

As can be seen in FIGS. 12, 13, and 14, the plate 330 has in its central region an axial passsge 390 for the lower portion of the rod of the button 312 and for the zone 392, which has a generally triangular profile, of the unit 325 whose inclined face constitutes the inclined plane 346.

In order to effect the downward movement of the plate 330, the rod 337 of the operating button has two diametrically opposed projections 395 (FIG. 12a) which project laterally from each side of the passage 390 (FIG. 14) and consequently effect the driving of the latter downwards together with the button 312 when they come into contact with the upper face of the retaining plate 376.

The position of the projections 395 along the rod 337 is so selected that they make contact with the retaining plate 376 only when the stud 347 has passed over the entire length of the inclined plane 346, that is to say when the tube carrier unit has performed its entire movement of translation towards the left. The ejection rods are then situated exactly in the axis of the ejection passages 322, at the entry of each of which this movement of translation has effected the positioning of an antibiotic disc (not shown). When the downward movement of the button 312 continues, the relative positions of the unit 325 and plate 330 in relation to the base 320 are maintained by the stud 347 in cooperation with the wall 346a, which extends the inclined plane 346 downwards parallel to the axis of displacement of the button 312. The downward movement of the ejection rods in the passage 322 then effects the simultaneous discharge of sixteen antibiotic discs and their deposition against the surface of the agar medium contained in the Petri dish disposed under the base (FIGS. 15 and 16).

Because of the various return springs, the same relative displacements of the plate 330 in relation to the unit 335 and then of these two elements in relation to the base 320 take place in the reverse order when the operating button of the distributor is released.

As is known per se, the disc carrier tubes 314 have a generally cylindrical hollow body 400 inside which the discs 401 are stacked, a compression spring 402 urging the discs towards the bottom of the tube.

This being the case, the operation of the distributor effects the simultaneous ejection of a disc from each tube only as long as none of the tubes is empty, and whenever it is not absolutely certain that all the tubes originally contained the same number of discs it is convenient to make sure, after ejection, that the number of discs deposited on the agar medium is actually equal to the number of tubes.

In order to make this check unnecessary, there may advantageously be provided in each tube, between the spring 402 and the stack of discs 401, an element, such as the locking finger 405 shown in FIG. 2, which comprises a cylindrical base portion 406 the lower face of which is extended axially downwards to form a cylindrical nipple 407 having a rounded end and the diameter of which is slightly less than the distance separating the two retaining projections provided at the base of each of the tubes.

As illustrated in FIG. 22 by the tube 317a. the finger 405 plays no part in the operation of the distributor as long as the tube still contains discs.

However, as soon as the movement of translation of the tube carrier unit to the right extracts from one of these tubes the last disc contained in it (tube 317b) in FIG. 22, the rounded end of the corresponding nipple 407 comes to bear directly against the projection 350 facing it (FIG. 15), and it slides against the said projection until the tube carrier unit has reached the end of its travel (towards the left in the drawings). As likewise illustrated in FIG. 22, it is possible to provide in the base a locking bore 410 in line with the position then occupied by each tube. The nipple 407 of the tube 317b will in this case be engaged in the corresponding bore 410, whereby the locking of the tube carrier unit in its operative position is effected. The ejection rods can then descend normally in the passages 322, but the release of the operating button 312 will not bring about the return of the tube carrier unit to its position of rest, so that the operator will be warned that at least one of the tubes is empty.

In order to resume operation of the distributor, it is sufficient to withdraw the empty tube or tubes 317b,

which can easily be located by examining the bottom face of the base, since the nipple or nipples 407 will be visible at the bottom of the bores 410.

These arrangements are naturally applicable both when the tube carrier unit is adapted to perform a movement of translation, as in the case of the distributor described above, and when this unit is a rotating drum as described with reference to the arrangements shown in FIGS. 1 to 11.

Although for the purpose of effecting the locking function described above it is advantageous for each finger 405 to co-operate with a bore 410 reserved for this purpose, it will be noted that the presence of this bore is not essential.

If in fact the bores 410 are provided, the nipple 407 of the empty tube or tubes 317b will penetrate into the passage 322 when the tube carrier unit returns to its position of rest, in which the unit will then remain blocked, with the same result as previously described, once again making it possible to locate the empty tube or tubes by examining the bottom of the passages 322.

We claim:

1. A distributor for discs or pastilles, of the kind intended to deposit simultaneously on the surface of an agar medium a plurality of the said discs or pastilles in a predetermined configuration, comprising a base having an upper face and a lower face and also a plurality of suitably spaced ejection passages extending between the said faces; a tube carrier unit provided with a corresponding plurality of sockets for tubes containing the said discs or pastilles and with a plurality of guide bores, the said unit having a bottom face adapted to cooperate with the upper face of the base to effect, through the relative displacement of the said bottom face parallel to the said upper face, the extraction of a disc or pastille at the bottom of each of the tubes mounted in the said sockets and the positioning of the said disc in line with the top end of a corresponding ejection passage; a plurality of ejection rods each of which is received for axial sliding in one of the said guide bores for the purpose of co-operating with one of the said ejection passages in each case; and an operating element mounted for axial sliding at right angles to the upper face of the said base, the said operating element being kinematically associated with the said tube carrier unit and with the said ejection rods in such a manner as to make it possible to effect in succession the aforesaid relative displacement of the tube carrier unit and the penetration of the ejection rods through the said ejection passages.

2. A distributor according to claim 1, wherein the upper face of the base has extraction and positioning projections disposed on each side of each ejection passage of the said base in such a manner as to co-operate with the bottom of each tube received in the said tube carrier unit, for the purpose of effecting the extraction of a disc and retaining it in line with the corresponding ejection passage through the action of the said relative displacement.

3. A distributor according to claim 1, wherein the said base has a body of a generally cylindrical shape and the said tube carrier unit is a drum of generally cylindrical shape which is mounted for free rotation of the said base, the said drum being kinematically fixed in rotation to the said operating element by the said ejection rods and with the aid of a crown supporting the upper end of each of the said ejection rods.

4. A distributor according to claim 3, wherein the said base has a support ring adapted to be laid on the edge of a Petri dish or the like of circular shape, the said ring being screwed on the periphery of the body of the said base in such a manner as to permit the adjustment of the height of the distributor above the surface of the agar medium contained in the said dish.

5. A distributor according to claim 3, wherein the said drum has a first series of axial bores to receive each of the tubes, alternating with a second series of axial bores for the passage of the said ejection rods and the transmission to the drum, through the said rods, of the angular displacement of the said crown.

6. A distributor according to claim 3, wherein the said base has a first axial extension adapted to effect the external guiding of the drum in respect of rotation, and a second axial extension adapted to effect the guiding of the operating element in respect of movement of translation and the internal rotational guiding of the drum.

7. A distributor according to claim 3, comprising cam means adapted to impart the aforesaid rotation to the drum when an axial pressure in the direction of the base is applied to the said operating element.

8. A distributor according to claim 7, wherein the said cam means comprises a profiled groove cooperating with a pin, the said groove and the said pin being respectively solid with an axial extension of the said base and with an axial extension of the said operating element.

9. A distributor according to claim 7, wherein the said cam means comprises a profiled groove cooperating with a pin, the said groove and the said pin being respectively solid with an axial extension of the said operating element and with an axial extension of the said base.

10. A distributor according to claim 7, wherein the said operating element has a head mounted for free rotation on the aforesaid crown.

11. A distributor according to claim 1, wherein the said ejection rods comprise a push-rod adapted for sliding between a retracted position and a position of extension in the bottom end of a socket which by its top end is associated with the aforesaid operating element, the said push rod being loaded by a spring adapted to cause it to apply to the surface of the aforesaid agar medium a pressure lower than a predetermined value.

12. A distributor according to claim 11, wherein the free end of the said push rod is provided with a support shoulder having a radial width substantially equal to the thickness of the wall of the said sleeve.

13. A distributor according to claim 1, wherein the said tube carrier unit is mounted for free movement of translation on the upper face of the aforesaid base, be-

tween a position of rest in which the axis of each ejection passage of the said base is substantially in line with the axis of a corresponding socket in the said unit, and a working position in which the axis of the said passage is substantially in line with the axis of a corresponding guide bore in the said unit, and the said ejection rods are carried by a plate mounted on the said base in such a manner as to be able to slide in relation to the said base, parallel to the axis of the said ejection passages.

14. A distributor according to claim 13, wherein the upper face of the said base is provided, on each said of each of the said ejection passages, with projections adapted to co-operate with the tubes disposed in the said sockets, in order to effect the extraction and retention of a disc or pastille in line with each ejection passage when the tube carrier unit passes from its position of rest to its working position, and a face of the said unit which is adjacent to the said base has at least one groove adapted to co-operate with at least one corresponding said projection for the purpose of effecting the guiding of the said unit in respect of movement of translation.

15. A distributor according to claim 13, wherein the aforesaid operating element comprises an operating rod mounted for sliding on the said base between a position of rest and a working position, the said rod cooperating with an inclined plane on the said tube carrier unit in such a manner as to effect the translational movement of the said unit from one to the other of its two said positions when the said rod is caused to slide along a first portion of its operating travel, starting from the said position of rest, the said rod having at least one projection arranged to come into contact with the said plate in order to effect the displacement of the plate conjointly with the displacement of the said rod along a second portion of the operating travel in the direction of its working position.

16. A distributor according to claim 13, wherein the said plate comprises two adjacent plates joined together, one of which is provided with sockets each of which is adapted to receive, with slight axial play, one of the ends of corresponding ejection rod, and the said ejection rods comprises a sleeve having an open end received in a corresponding one of the last-mentioned sockets, and also a compression spring disposed in the said sleeve.

17. A disc carrier tube for operating a distributor according to claim 1, the said tube comprising a generally cylindrical hollow body, an elastic element adapted to compress a stack of discs received in the second tube for the purpose of lateral extraction at the bottom of the latter, and a locking element interposed between the said elastic element and the said stack, and adapted to project from the bottom of the said tube after extraction of the last disc of the said stack.

18. A tube according to claim 17, wherein the said locking element comprises a cylindrical body of which one face bears against the said elastic element while its opposite face is extended coaxially in the form of a nipple having a rounded end.

19. A distributor for discs or pastilles of the kind intended to deposit simultaneously, on the surface of an agar medium, a plurality of the said discs in a predetermined configuration, comprising a base provided with a plurality of ejection passages, a tube carrier unit provided with a plurality of sockets for tubes containing the said discs or pastilles and with a plurality of guide bores, the said unit being adapted to move between two positions, in relation to the said base, in order to present in line with each of the said passages a corresponding socket or a corresponding bore, a plurality of ejection rods each of which is received for axial sliding in one of the aforesaid guide bores in order to co-operate with one of the said passages, and operating means adapted to effect the displacement of the said unit in relation to the said base and the displacement of the said ejection rods in relation to the said unit, the said base additionally comprising a plurality of locking bores each of which is adapted to co-operate with a locking element which may be provided in the said tubes in such a manner as to effect the locking of the said tube carrier unit in relation to the said base through the engagement of the said locking element in the said locking bore.

20. A distributor according to claim 19, wherein the said locking bores are provided in line with the situation occupied by the said tubesin the said tube carrier unit when the said ejection rods are situated in line with the said ejection passages.

21. A distributor according to claim 19, wherein the said locking bores are open at their two ends for the purpose of permitting the detection of an empty tube by inspection of the bottom face of the said base. 

1. A distributor for discs or pastilles, of the kind intended to deposit simultaneously on the surface of an agar medium a plurality of the said discs or pastilles in a predetermined configuration, comprising a base having an upper face and a lower face and also a plurality of suitably spaced ejection passages extending between the said faces; a tube carrier unit provided with a corresponding plurality of sockets for tubes containing the said discs or pastilles and with a plurality of guide bores, the said unit having a bottom face adapted to co-operate with the upper face of the base to effect, through the relative displacement of the said bottom face parallel to the said upper face, the extraction of a disc or pastille at the bottom of each of the tubes mounted in the said sockets and the positioning of the said disc in line with the top end of a corresponding ejection passage; a plurality of ejection rods each of which is received for axial sliding in one of the said guide bores for the purpose of co-operating with one of the said ejection passages in each case; and an operating element mounted for axial sliding at right angles to the upper face of the said base, the said operating element being kinematically associated with the said tube carrier unit and with the said ejection rods in such a manner as to make it possible to effect in succession the aforesaid relative displacement of the tube carrier unit and the penetration of the ejection rods through the said ejection passages.
 2. A distributor according to claim 1, wherein the upper face of the base has extraction and positioning projections disposed on each side of each ejection passage of the said base in such a manner as to co-operate with the bottom of each tube received in the said tube carrier unit, for the purpose of effecting the extraction of a disc and retaining it in line with the corresponding ejection passage through the action of the said relative displacement.
 3. A distributor according to claim 1, wherein the said base has a body of a generally cylindrical shape and the said tube carrier unit is a drum of generally cylindrical shape which is mounted for free rotation of the said base, the said drum being kinematically fixed in rotation to the said operating element by the said ejection rods and with the aid of a crown supporting the upper end of each of the said ejection rods.
 4. A distributor according to claim 3, wherein the said base has a support ring adapted to be laid on the edge of a Petri dish or the like of circular shape, the said ring being screwed on the periphery of the body of the said base in such a manner as to permit the adjustment of the height of the distributor above the surface of the agar medium contained in the said dish.
 5. A distributor according to claim 3, wherein the said drum has a first series of axial bores to receive each of the tubes, alternating with a second series of axial bores for the passage of the said ejection rods and the transmission to the drum, through the said rods, of the angular displacement of the said crown.
 6. A distributor according to claim 3, wherein the said base has a first axial extension adapted to effect the external guiding of the drum in respect of rotation, and a second axial extension adapted to effect the guiding of the operating element in respect of movement of translation and the internal rotational guiding of the drum.
 7. A distributor according to claim 3, comprising cam means adapted to impart the aforesaid rotation to the drum when an axial pressure in the direction of the base is applied to the said operating element.
 8. A distributor according to claim 7, wherein the said cam means comprises a profiled groove co-operating with a pin, the said groove and the said pin being respectively solid with an axial extension of the said base and with an axial extension of the said operating element.
 9. A distributor according to claim 7, wherein the said cam means comprises a profiled groove co-operating with a pin, the said groove and the said pin being respectively solid with an axial extension of the said operating element and with an axial extension of the said base.
 10. A distributor according to claim 7, wherein the said operating element has a head mounted for free rotation on the aforesaid crown.
 11. A distributor according to claim 1, wherein the said ejection rods comprise a push-rod adapted for sliding between a retracted position and a position of extension in the bottom end of a socket which by its top end is associated with the aforesaid operating element, the said push rod being loaded by a spring adapted to cause it to apply to the surface of the aforesaid agar medium a pressure lower than a predetermined value.
 12. A distributor according to claim 11, wherein the free end of the said push rod is provided with a support shoulder having a radial width substantially equal to the thickness of the wall of the said sleeve.
 13. A distributor according to claim 1, wherein the said tube carrier unit is mounted for free movement of translation on the upper face of the aforesaid base, between a position of rest in which the axis of each ejection passage of the said base is substantially in line with the axis of a corresponding socket in the said unit, and a working position in which the axis of the said passage is substantially in line with the axis of a corresponding guide bore in the said unit, and the said ejection rods are carried by a plate mounted on the said base in such a manner as to be able to slide in relation to the said base, parallel to the axis of the said ejection passages.
 14. A distributor according to claim 13, wherein the upper face of the said base is provided, on each said of each of the said ejection passages, with projections adapted to co-operate with the tubes disposed in the said sockets, in order to effect the extraction and retention of a disc or pastille in line with each ejection passage when the tube carrier unit passes from its position of rest to its working position, and a face of the said unit which is adjacent to the said base has at least one groove adapted to co-operate with at least one corresponding said projection for the purpose of effecting the guiding of the said unit in respect of movement of translation.
 15. A distributor according to claim 13, wherein the aforesaid operating element comprises an operating rod mounted for sliding on the said base between a position of rest and a working position, the said rod co-operating with an inclined plane on the said tube carrier unit in such a manner as to effect the translational movement of the said unit from one to the other of its two said positions when the said rod is caused to slide along a first portion of its operating travel, starting from the said position of rest, the said rod having at least one projection arranged to come into contact with the said plate in order to effect the displacemeNt of the plate conjointly with the displacement of the said rod along a second portion of the operating travel in the direction of its working position.
 16. A distributor according to claim 13, wherein the said plate comprises two adjacent plates joined together, one of which is provided with sockets each of which is adapted to receive, with slight axial play, one of the ends of corresponding ejection rod, and the said ejection rods comprises a sleeve having an open end received in a corresponding one of the last-mentioned sockets, and also a compression spring disposed in the said sleeve.
 17. A disc carrier tube for operating a distributor according to claim 1, the said tube comprising a generally cylindrical hollow body, an elastic element adapted to compress a stack of discs received in the second tube for the purpose of lateral extraction at the bottom of the latter, and a locking element interposed between the said elastic element and the said stack, and adapted to project from the bottom of the said tube after extraction of the last disc of the said stack.
 18. A tube according to claim 17, wherein the said locking element comprises a cylindrical body of which one face bears against the said elastic element while its opposite face is extended coaxially in the form of a nipple having a rounded end.
 19. A distributor for discs or pastilles of the kind intended to deposit simultaneously, on the surface of an agar medium, a plurality of the said discs in a predetermined configuration, comprising a base provided with a plurality of ejection passages, a tube carrier unit provided with a plurality of sockets for tubes containing the said discs or pastilles and with a plurality of guide bores, the said unit being adapted to move between two positions, in relation to the said base, in order to present in line with each of the said passages a corresponding socket or a corresponding bore, a plurality of ejection rods each of which is received for axial sliding in one of the aforesaid guide bores in order to co-operate with one of the said passages, and operating means adapted to effect the displacement of the said unit in relation to the said base and the displacement of the said ejection rods in relation to the said unit, the said base additionally comprising a plurality of locking bores each of which is adapted to co-operate with a locking element which may be provided in the said tubes in such a manner as to effect the locking of the said tube carrier unit in relation to the said base through the engagement of the said locking element in the said locking bore.
 20. A distributor according to claim 19, wherein the said locking bores are provided in line with the situation occupied by the said tubes in the said tube carrier unit when the said ejection rods are situated in line with the said ejection passages.
 21. A distributor according to claim 19, wherein the said locking bores are open at their two ends for the purpose of permitting the detection of an empty tube by inspection of the bottom face of the said base. 